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Saturday, 21 May 2016

Microwave oven

The microwave oven is a by-product of another technology. Dr. Percy Spencer, an engineer with the Raytheon Corporation, regularly used magnetrons to generate the microwave radio signals that are the core mechanism of radar, One day in 1945 he noticed they had melted a candy bar in his pocket and an intrigued Spencer tried another experiment. This time he placed some popcorn kernels near the tube and he watched as the popcorn cracked, sputtered and popped all over his lab. In another experiment he applied the magnetron to an egg, which exploded in the face of one of the experimenters.

Dr Spencer then created the first true microwave oven by attaching a high density electromagnetic field generator to an enclosed metal box. The magnetron emitted microwaves into the metal box blocking any escape, allowing for controlled and safe experimentation. He then placed various food items in the box, while observing effects and monitoring temperatures.

By the end of the year, the first prototype had been built. Raytheon filed a patent on October 8, 1945 for a microwave cooking oven. It was 5ft 6 ins tall and weighed 700lb.

In 1947 the first commercially produced microwave ovens were manufactured. Housed in refrigerator-sized cabinets, and costing about US$5,000, they were called the "Radarange," the winning name in an employee contest.

In 1952 Raytheon licensed microwave technology to Tappan. The company started selling the first domestic-use microwave oven in America three years later. Housed in a refrigerator-sized cabinet, they retailed for a price of US$1,295,  but these units were still too large and expensive for general home use.

The first commercial microwave ovens went on sale in the United Kingdom in 1958.

Raytheon RadaRange aboard the NS Savannah nuclear-powered cargo ship, installed circa 1961. By Acroterion -Wikipedia Commons

In 1965, Raytheon acquired the Amana Corporation and two years later, they introduced the first countertop microwave oven. The Radarange was the first relatively affordable ($495) and reasonably sized microwave oven made available for sale, It helped begin a rapid growth of the market for home microwave ovens

1971 Radar Range [RR-4]. By Pamperchu - Wikipedia Commons

Sales of microwave ovens exceeded that of gas ranges worldwide for the first time in 1975.

A typical microwave oven uses more electricity keeping its digital clock on standby than it does heating food.

Microwaves are "non-ionising" radiation, meaning they are too low-energy to damage DNA. So your microwave could give you a nasty burn, but only in the same manner as your oven.

Ants can survive in a microwave: they are small enough to dodge the rays.

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